From the perspective of disaster recovery, a storage system in which data is managed in a plurality of sites by using journal data is proposed. The contents of a primary volume which a primary site comprises are copied to a secondary volume in a secondary site at a physically distant location by using journal data (Patent Literature 1). By this method, the processing required for business can be continued even if a failure occurs in either the primary site or the secondary site.
It should be noted that, although this is not directly related to the storage system, in case a data transfer amount increases, a technology of using a spare line in addition to a regularly used line (Patent Literature 2) and a technology of automatically adjusting a transfer speed based on whether transfer between the computer and external apparatuses succeeded or not (Patent Literature 3) are known.